Why, oh why can't Hollywood leave a good thing alone? It seems that any TV show you ever loved eventually gets recycled into a big-budget, big-screen version ... and that's not always an improvement.

As often as these TV-to-movies misfire, we can bet more ideas are in the works, some of them sure to be good fun ('Transformers,' anyone?) and others destined to tarnish your fond memories of cult classics forever. Here's a look at some of the worst offenders in the latter category -- our countdown of the 25 worst movies based on TV shows. -- By Liane Bonin

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25. 'Josie and the Pussycats' (2001)In the 1970 animated series, Josie and her pals are pop music stars who just happen to solve mysteries in their free time. Not exactly rich dramatic fodder, but the movie struggled to find meaning with snarky commentary on the music industry and an evil scheme to brainwash the public with marketing messages. But it wasn't enough to save a really bad remake idea. And did we mention Tara Reid? (Rotten Tomatoes Rating: 53)

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24. 'Sgt. Bilko' (1996)On 'The Phil Silvers Show,' Sgt. Ernie Bilko is a con man who's always working an angle at a Kansas army camp. A hit in 1955, by the time the movie rolled around with Steve Martin in Silvers' shoes, audiences weren't feeling much nostalgia for cutesy military humor or a black-and-white TV show they'd never seen. (Rotten Tomatoes Rating: 32)

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23. 'Dennis the Menace' (1993)Even Walter Matthau as grumbly neighbor Mr. Wilson couldn't help this stinker. Hoping to spice up the conflict between mischievous Dennis and Mr. Wilson, writer John Hughes decided to throw in a real menace with town robber Switchblade Sam. Like we needed to see 'Home Alone' with a slightly different blond kid. (Rotten Tomatoes Rating: 25)

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22. 'The Saint' (1997)Before Ian Fleming created Bond, there was 'The Saint,' an equally dashing thief with a mysterious past. So what does Bond have that 'The Saint' doesn't? Plenty, it turns out. In this very unsaintly movie, a yawn-worthy plot, dull action scenes and a curiously restrained performance by Val Kilmer made audiences pine for the 1962 original starring Roger Moore. (Rotten Tomatoes Rating: 30)

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21. 'The Flintstones' (1994)Sure, everyone loves Fred and Wilma and their modern stone age family, but after an episode or two, we all realized it was just a pale imitation of 'The Honeymooners.' Unfortunately, the live action movie was just a pale imitation of the cartoon, though John Goodman, always the perfect shlubby husband on 'Roseanne,' brought Jackie Gleason-worthy bluster to his turn as Fred. (Rotten Tomatoes Rating: 18)

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20. 'Speed Racer' (2008)Take some retro Japanese anime, add the Wachowski brothers ('The Matrix') and you get ... an overblown, high-budget mess. We're sure it sounded like a good idea on paper, but the movie version is almost too true to the animated original, which lacked character, plot and logic. Dragged out to more than two hours, this bubblegum-colored special-effects explosion is just painful. (Rotten Tomatoes Rating: 36)

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19. 'Mr. Magoo' (1997)Maybe it was fun to laugh at the legally blind in 1960, but the adventures of this nearsighted millionaire got old fast for most people over the age of 8. Leslie Nielsen tried to bring his bumbling 'Airplane' persona to the movie version, but sadly, it still wasn't funny. (Rotten Tomatoes Rating: 4)

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18. 'McHale's Navy' (1997)Of course, WWII is always funny, so who couldn't yuk it up over a bunch of misfits floating around the South Pacific with a Japanese house boy? Sadly, while the series had talents like Ernest Borgnine, Tim Conway and Gavin McLeod to lighten the mood, the movie version had ... Tom Arnold. (Rotten Tomatoes Rating: 4)

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17. 'Fat Albert' (2004)Aside from some brilliant casting ('SNL' star Kenan Thompson was made to play Fat Albert), this movie is like school on Saturday: no class. Fans who loved the funky '70s original will find the movie version -- in which Albert and his animated pals jump out of a television to help a girl battle with loneliness -- bland at best, dumb kid stuff at worst. (Rotten Tomatoes Rating: 21)